This invention relates to improvements in a driving apparatus comprising elliptic gear wheels and has for its objective a modified elliptic gear wheel driving apparatus wherein the change in a gearing pressure angle of the gear wheels caused by the rotation thereof is reduced so as to relieve actual gearing pressure between the gear wheels, and said gear wheels are not only kept at a good gearing state by preventing trapping between meshed gear teeth and causing a scoring phenomenon, but also driving conditions are improved by increased gear meshing with constant pressure angle and torque so as to eliminate a pressure load on the gear face of a short axis side at higher rotation speed.
A gear face of a major axis side, formed of an involute shape, can be kept meshing on a lower rotation speed without out of meshing.
In the old elliptic gear wheels, in which both sides of a gear shape have a same form such as an involute gear shape or a cycloid gear shape, problems exist of trapping or out of meshing.
Whereas, according to this invention, in order to eliminate trapping between meshed gear teeth and also meshing gear rotors can be kept transfering torque of each of the rotors.
Conventional technology: A rotation body of an elliptic gear wheel type flow meter has involute gears or cycloid gears set up on a pich line. Both pitch lines of rotors are mashed with each other rotate naturally without slip. Coupled rotors can be installed in a measuring chamber in which a liquid to be measured is filled up and the rotor can be rotated. In this way, fluid liquid is measured by counting of a rotation of the rotors.
A rotor of conventional involute gear teeth type has a defect of wearing by a scoring phenomenon, especially in the case of non-lubrication. A strong pressure by trapping will be added on surfaces of meshed gear teeth.
Such worn rotors can no longer indicate precise flow rate. A characteristic curve shows increased error.
In a flow meter installation of coupled rotors of an involute gear form, a pressure angle of meshed gear rotors keeps a constant value in rotation and a back rush between both meshed teeth keeps constant.
A trapping space occurs when rotation changes to a high speed from a low speed and, a point that contacts a tooth form changes. Therefore, liquid trapped in the space is returned to a side of an entrance. When rotor speeds change to a high speed, an inertia of the rotor changes and affects the effectiveness.
Although a characteristic curve of flow meter shows a singular decrease by this phenomenon, a rotor settled with cycloid gear form and the like eliminates such defect and shows an excellent characteristic character.
A rotor in which a cycloid gear form settled on a pitch line rotates mutually can eliminate such trapping by an addendum or addendum of gear form.
A pressure angle mutually meshed on top of a gear tooth and/or a bottom of a gear form on a pitch line distance is larger compared with that of the pitch point and thus a clearance between meshing gear forms are increased. An increased angle of meshing gear teeth point of the rotor against a designed backlash of gear rotors causes a time lag for conversion of meshing and a leak of fluid increases. Thus an error is increased.
A torque of a meshed gear rotor is effective in low speed. A momentum of inertia is effective work when rotating speed of rotor is higher speed. A speed of conversion of meshing is about 100 rpm to 150 rpm.